CVE-2018-17204 [Medium] | Security Vulnerability in Openvswitch

An issue was discovered in Open vSwitch (OvS) 2.7.x through 2.7.6, affecting parse_group_prop_ntr_selection_method in lib/ofp-util.c. When decoding a group mod, it validates the group type and command after the whole group mod has been decoded. The OF1.5 decoder, however, tries to use the type and command earlier, when it might still be invalid. This causes an assertion failure (via OVS_NOT_REACHED). ovs-vswitchd does not enable support for OpenFlow 1.5 by default.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2025-11-21	1.31%	1.13%	-0.19%
2	2025-11-18	1.13%	1.31%	+0.19%
3	2025-08-20	—	1.13%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2025-11-21

1.31%

1.13%

-0.19%

2025-11-18

1.13%

1.31%

+0.19%

2025-08-20

—

1.13%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
4.3	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	2.8	1.4	[email protected]
4.0	2.0	MEDIUM	`AV:N/AC:L/Au:S/C:N/I:N/A:P` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:S) A single authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:N) No integrity impact. Availability impact (A:P) Partial availability impact.	8.0	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

4.3

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

2.8

1.4

[email protected]

4.0

2.0

MEDIUM

AV:N/AC:L/Au:S/C:N/I:N/A:P Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:S): A single authentication is required.
Confidentiality impact (C:N): No confidentiality impact.
Integrity impact (I:N): No integrity impact.
Availability impact (A:P): Partial availability impact.

8.0

2.9

[email protected]

OS Trackers for CVE-2018-17204

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2018-17204 not yet assigned priority: Debian including 1 source packages (openvswitch), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2018-17204
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2018-17204
`suse`	medium	—	https://www.suse.com/security/cve/CVE-2018-17204/
`ubuntu`	medium	CVE-2018-17204 medium priority: Ubuntu including 1 source packages (openvswitch), 5 status rows across 5 suites (bionic, cosmic, trusty, upstream, xenial): released 2, DNE 1, needs-triage 1, not-affected 1.	https://ubuntu.com/security/CVE-2018-17204

Affected software / configurations for CVE-2018-17204

Vendor	Product	Version	Raw CPE
openvswitch	openvswitch	>= 2.7.0, <= 2.7.6	cpe:2.3:a:openvswitch:openvswitch::::::::
redhat	openstack	10	cpe:2.3:a:redhat:openstack:10:::::::*
redhat	openstack	13	cpe:2.3:a:redhat:openstack:13:::::::*
canonical	ubuntu_linux	16.04	cpe:2.3:o:canonical:ubuntu_linux:16.04::::lts:::
canonical	ubuntu_linux	18.04	cpe:2.3:o:canonical:ubuntu_linux:18.04::::lts:::
debian	debian_linux	9.0	cpe:2.3:o:debian:debian_linux:9.0:::::::*

References for CVE-2018-17204

URL	Tags
https://access.redhat.com/errata/RHSA-2018:3500	Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:0053	Third Party Advisory
https://access.redhat.com/errata/RHSA-2019:0081	Third Party Advisory
https://github.com/openvswitch/ovs/commit/4af6da3b275b764b1afe194df6499b33d2bf4cde	Patch Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/02/msg00032.html	Mailing List Third Party Advisory
https://usn.ubuntu.com/3873-1/	Third Party Advisory

URL

CVE-2018-17204

Exploit prediction scoring system (EPSS) score for CVE-2018-17204

Common vulnerability scoring system (CVSS) metrics for CVE-2018-17204

Weakness enumeration for CVE-2018-17204

OS Trackers for CVE-2018-17204

Affected software / configurations for CVE-2018-17204

References for CVE-2018-17204